Patent GB-811721-A (GB)
Title: Improvements relating to transparent thermoplastic synthetic organic polymeric sheeting
IPC: B32B17/10
Filed: 1955-08-02
Abstract: <PICT:0811721/IV (a)/1> <PICT:0811721/IV (a)/2> <PICT:0811721/IV (a)/3> <PICT:0811721/IV (a)/4> <PICT:0811721/IV (a)/5> <PICT:0811721/IV (a)/6> <PICT:0811721/IV (a)/7> <PICT:0811721/IV (a)/8> Cut insert sheets for use in laminated glass are made by continuously feeding transparent sheeting of a polymer, such as a polyvinyl resin, in web form from a roll thereof to a drying zone, drying the web to remove moisture and traces of volatile material, cooling the web after it has been heated and dried, washing the web to soften it and remove traces of chemical deposits, stripping the web of liquid to dry it, conveying the web while heating it to remove moisture and to relax it from any stretching occurring in the prior steps, directing air blasts on to the web to remove further moisture and to cause the web to shrink and thereby become taut as it is being conveyed, conveying the web through a cold zone to chill and set the web, cutting out inserts in the desired pattern for laminating from the chilled and set web and then stripping the cut inserts from the rest of the web.  As shown in Figs. 1-1b, the web W is fed from a roll of stock V by a feed-in frame 10 successively through a festoon drier 40, a cooling chamber 61, and a tension control station 80, where a uniform tension is maintained on the web as it enters a washer 110.  As the web leaves the washer it is stripped of water by the rolls 119, 120 and is carried by a drying and cooling conveyer 130 to a cooling room 160 where it is chilled and set.  The web, after leaving the chill room 160, has inserts in pattern form cut therefrom by a die press 180 and, after leaving the press, is carried by a take-off conveyer 200, where the inserts are stripped from the balance of the web.  The feed-in frame generally indicated at 10 in Figs. 1-4 is provided with spaced-apart bed rollers 13 on which is mounted the mandrel 9 which protrudes at each end from the roll of stock V.  The web W is fed between a pair of rubber rolls 15, 151, roll 15 being driven by an electric motor M through a belt 17 and a pulley 18.  Pivoted about the roll 151 is a pair of oppositely extending arms 19, which are connected together by a transverse bar 191 at one end and support at the other end a driven roll 20.  Roll 20 is driven by roll 151 through belt 21 and pulley 211.  A pair of limit switches ls1 and ls2 are supported on the bracket 23 attached to the frame of the machine (Fig. 3).  Limit switch ls1 is connected in circuit with the motor M and, as the roll V of stock unrolls under the influence of the drive roll 20, arm 19 is lowered as the roll V becomes smaller.  Before roll V is fully unrolled, arm 19 contacts limit switch ls1, speeding up motor M, roll 20 and roll V so that the web W is run off at a greater speed than is demanded by the drier.  A stock of web is consequently accumulated in bin 24 so that a new roll of stock may be spliced on to the end of the web on roll V without interrupting the travel of the web through the remainder of the apparatus.  Arm 19 continues to pivot downwards as the stock on roll V is further diminished and finally strikes limit switch ls2, whereupon motor M is stopped.  This permits the operator to pull off the end of the stock on roll V, insert a new mandrel with a new roll of stock and splice on the end of the unwound web.  Also mounted on the frame 10 are a pair of inductance coils, generally indicated at 25, 26 (Fig. 3), having an armature 27 which is pivotally connected at its upper end to an operating lever 28 pivoted at 281 on bracket 14.  Lever 28 is connected by an intermediate link 29 by a pivot means at each end to one of a pair of tension-sensing arms 30 pivoted to bracket 14, as at 31.  Arms 30 support at one end a metal roller 32 and at the other end a cross-bar 33 which carries counterweights 331 Fig. 4).  Roller 32 rides on web W (Fig. 1) and, through the tension sensing arms 30, the linkages 29, 28 move armature 27, which controls the inductance coils 25, 26, which respectively speed-up and slow-down motor M and thus maintain the tension of the web at a set predetermined value.  On an extreme tension being applied to the web, arm 30 pivots upwardly and contacts limit switch ls3, which is connected in a trip circuit with the motor M and the drive motors on the drier, washer and conveyer, as described below.  The web is next fed through a drier, generally indicated at 40 (Fig. 1), which has a pair of associated guide rolls 41, 42 between which the web is trained before it passes over a number of vertically-spaced and horizontally offset alternate rolls 43, the upper row of which is driven through a pulley 62, belt 63 and common drive 54.  The drier is provided with vertically-extending compartments 44, 45 (Fig. 5), at either side and at the ends of rolls 43.  Each of these compartments contains steam coils 46 for heating air circulated by the banks of fans 47, 48 mounted in the upper ends of the heating compartments 44, 45.  This heated air is circulated through the drier proper 49 containing the rollers 43.  Air is withdrawn from the chambers 44, 45 through ducts 50, 51 and exhausted to the atmosphere by exhaust blower 52.  After leaving the drier 40 the web is carried through a horizontally-disposed cooling chamber 61 by a conveyer 60 of the endlessbelt type. This conveyer is driven by an electric motor M2 through an infinitely variable speed gear 70 (Figs. 1a and 8) which has an output shaft 71 mounting a drive pulley 711 which drives, through a belt 64 at the delivery end of the conveyer 60, a pulley 65 fixedly mounted on a shaft 66 at the delivery end of the conveyer.  The variable gear 70 includes a pair of pulleys 72, 721 (Fig. 8), controlled by the arm 73 pivotally connected to the screw member 74 through a nut 741 and pivoted at a point P halfway between the pulleys.  The pulleys 72, 721 are of the type in which one flange is fixedly mounted on the pulley shaft but the other flange is separate from the first and is independently mounted on the shaft in such a manner that, while it is rotated by the shaft, it can be moved axially along the shaft, e.g. on splines, nearer to or further away from the first or fixed flange.  The pulleys are adapted for a V-belt drive, and the effect of causing the movable flange to approach the fixed flange will therefore be to increase the effective diameter of the pulley, and vice versa.  In order that the tension of the V-belt may remain constant irrespective of the distances between the fixed and moving flanges, of each pulley, the flange-moving device is so arranged that, as one pulley "opens," the other "closes" to a corresponding degree, thus providing an infinitely variable gear drive with substantially constant belt tension.  Screw member or threaded shaft 74 is driven through belt 75 by means of a small reversible drive motor M76.  Nut 741 is pinned to arm 73 to prevent it from rotating, so that rotation of screw member 74 causes nut 741 to travel along the screw member and cause arm 73 to pivot about the fixed vertical spindle P.  Limit switches 77, 78 are associated with screw member 74 so that, when the nut 741 moves to either of the extreme limits of the threaded portion of screw member 74, motor M76 is reversed.  This motor is electrically connected to a photoelectric cell tension-control mechanism-shown in Figs. 1a and 9.  After leaving the conveyer 60 the web passes over a counter-balanced dancer roll 81 of the photo-electric cell tension control mechanism shown generally at 80 (see Group XXXV).  Roller 81 is guided in vertical movement between a pair of vertically disposed and spaced-apart support members 82, 83 positioned below the discharge end of the cooler 61, and is counter-balanced by a weight 84 attached to one end of a flexible strap 85 which is led over an idler roller 86. Vertical support member 87 carries light sources 89, 91 and upper and lower scanning means in the form of photo-electric sensing receivers 90, 92 are mounted on vertical support 88.  When the roller 81 has risen so that light from source 89 impinges on the photo-cell 90, limit switch 77 is closed and motor M76 is energized.  As soon as the lever 73 (Fig. 8) is moved by nut 141 to contact limit switch 77, that switch is opened and the motor M76 is stopped.  When light impinges on photo-cell 92, limit switch 78 is opened, which controls the downward movement of the roller 81.  As the web is pulled by the conveyer 130 through the stripper rollers 119, 120 and wash tank 110 it may move fast or slowly and cause dancer roll 81 to move up or down. The action of the roll 81 on photocells 90, 92 causes motor M76 to rotate ahead or in reverse and thus cause conveyer 60 to feed the web faster or more slowly into washer 110.  Thus the tension of the web between conveyer 60 and stripper rolls 119, 120 will be held between predetermined limits.  After leaving the automatic tension control mechanism 80 the web passes over a guide roll 113 mounted on top of the tank of warm soft water 11 of the washer 110 and then under bottom idler roll 115 and over guide rolls 114, 116 into the cold water spray tank 112.  In this tank the web is led under bottom rolls 117 vertically upward between oppositelypositioned pairs of cold water spray heads 118 and out through a pair of rubber water-stripping rolls 119, 120 urged together by a pneumatic actuator 121.  After passing over the guide roll 123 the web passes over the endless conveyer 130, which has rolls 131, 132 mounted at each end and is made up of stainless steel slats 1301.  Conveyer 130 is driven by electric motor M3 through an infinitely variable speed gear 133, belt 136 and pulley 135 attached to roll 131.  Roller 123 on the washer 110 is driven by roll 132 at the upper end of the conveyer 130 through drive pulley 137 and belt 138.  The upper and lower surfaces of the web are heated by heater elements 139, 140 at the upper end